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VOA慢速英语2013 埃博拉出血热的新疗法

时间:2013-11-18 11:29:57

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New Treatment Found for Ebola Fever 埃博拉出血热的新疗法

From VOA Learning English, this is Science in the News. I’m Bob Doughty1.

And I’m Faith Lapidus. Today we tell about Ebola hemorrhagic fever and a promising2 treatment for the disease. We also have a report about tuberculosis3 bacteria. Scientists now say human tuberculosis was present in Africa tens of thousands of years ago. We also tell about progress against a disease that threatens 20 percent of the world’s population.

Medical researchers have developed a promising treatment for Ebola hemorrhagic fever. The experimental compound could become the first successful treatment for Ebola. It helped even after signs of the disease developed.

Ebola hemorrhagic fever is spread by infected bats in western Africa. Right now, some forms of the virus kill about 90 percent of the people they infect. That is because by the time people show Ebola symptoms, little can be done to save them. The signs include high body temperature, breathing problems, and severe pain in the head or other body parts.

American scientists have developed an experimental treatment that could save lives. The researchers work with the Army Medical Research Institute of Infectious Diseases. Researcher James Pettitt says more than 40 percent of rhesus macaques were cured after they had already developed severe symptoms. The animals were treated with protective antibodies taken from specially4 grown tobacco plants. The treatment is called MB-003.

In an earlier experiment, MB-003 prevented symptoms in 100 percent of the monkeys when given one hour after coming in contact with the disease. This time, says Mr. Pettitt, investigators5 waited more than four days to treat the animals. They wanted to see how well the treatment might work in people who are infected with the disease.

The Ebola virus can quickly reproduce and overpower the patient’s immune cells, which protect the body against disease. But, MB-003 stops the virus by targeting a protein on its outer surface. This activates6 the person’s natural antibodies to kill infected cells.

James Pettitt says the American government is interested in the treatment because of the possible use of the Ebola virus for bioterrorism.

“That’s how it’s labeled by the Centers for Disease Control. So our mission is to protect the war fighter from any potential outbreaks from this in indigenous7 regions where they might be posted.”

He says researchers now want to try to increase the compound’s effectiveness, at the same time making sure it is safe and effective in humans.

A report about MB-003 as a possible treatment for infection with the virus was published in the journal Science Translational Medicine.

Tuberculosis Came From Africa

Scientists say they now have evidence that tuberculosis first appeared in Africa at least 70,000 years ago. Their finding conflicts with the current understanding of when and how tuberculosis came into being. Most scientists say the bacteria first appeared in animals only 10,000 years ago and later spread to human beings.

But now an international team of researchers claims it was the other way around. They say TB appeared in humans much earlier -- 60,000 years earlier -- and then spread to animals.

The team is under the direction of Sebastien Gagneux of the Swiss Tropical and Public Health Institute. He explains why it is important to study the history of TB.

“The idea is that by learning from the past and how infectious disease evolves over time, this potentially could give us some clue about the future of the TB epidemic8.” 

He notes that humans and TB did more than just grow side by side.

“I think that’s a nice way to put it. Maybe you can even say one inside the other. Imagine where the TB bacteria live, which is actually inside human bodies. Yes, side by side, or one inside the other.” 

Scientists know that people have bacteria on them and in them all the time. In fact, the bacteria help keep us alive. Researchers are attempting to learn if tuberculosis bacteria were always harmful to humans.

Scientists want to know why only five to 10 percent of the estimated two billion people infected with the bacteria actually come down with active tuberculosis. Another question is whether the bacteria were at one time good for human health?

“This idea that maybe carrying these bacteria in this latent form could potentially be beneficial because it might protect against other diseases. Again, that’s a very provocative9 hypothesis, which we, however, cannot completely neglect.” 

Professor Gagneux says TB left Africa when humans did, about 65 to 70 thousand years ago. Then, about 10 thousand years ago, came the Neolithic10 Demographic Transition. That is the period when people started to develop agriculture and to domesticate11, or train, animals. But, it was also a time when diseases jumped from domesticated12 animals to humans for the first time.

Professor Gagneux says for many years people thought that TB took the same path – from animals to humans. But, the research shows that TB first appeared in humans before the domestication13 of animals. In fact, the bacteria learned to live inside people and now cannot survive by itself in the environment.There was another important development during the Neolithic Demographic Transition. Humans started to form communities with lots and lots of people. That would have been ideal for the spread of tuberculosis through the air from person to person.

Professor Gagneux says before settlements, in the hunter-gatherer days, TB may not have been as deadly.

“Overly deadly would be a bad strategy for any pathogen because you might just kill off all susceptible14 hosts and you might end up with nobody else to infect.” 

After humans left Africa, they started to change in appearance as they reacted to new environments in other parts of the world. TB also changed and now there are many different forms of bacteria that cause the disease. The one found in South Africa differs from that found in China, but Africa still has the greatest number of TB strains. Researchers hope that knowing the history of TB will help in the development of new drug treatments and vaccines15. Now, the number of drug-resistant TB cases is growing. The knowledge may also help predict what the scientists are calling “future patterns of the disease.” 

Scientists are working on ways to stop a disease that threatens one-fifth of the world’s population. Over 120 million people are infected with lymphatic filariasis, also known as elephantiasis. The disease is found mainly in Southeast Asia and Africa. It affects the lymphatic system, which is a major part of the body’s natural defenses for fighting disease.

Elephantiasis can cause swelling16, or enlargement, of skin and tissue. The cause is a tiny worm that enters and lives in lymphatic tubes for six to eight years.

Scientists have been able to demonstrate that the most common cause of elephantiasis can be stopped. They are urging those at risk to sleep under nets treated with chemicals that kill a common insect: the mosquito.

Lisa Reimer teaches at the Liverpool School of Tropical Medicine. She formerly17 served in Papua New Guinea as part of a team studying the disease. Doctor Reimer says she was surprised at how effective anti-malaria18 bed nets covered with insecticide could be at fighting the disease.

“Filariasis is only picked up by mosquitoes late in the evening, so this is the time when people are more likely to be protected by their bed nets. So we found that bed net use actually is a greater barrier against filariasis transmission whereas malaria transmission may still be occurring outside the times when the user is under the net.”

Doctors normally use drugs to fight the disease. Lisa Reimer says doctors in Papua New Guinea gave the drugs to people of five villages. She says this treatment nearly ended the threat from the worm to humans. But the drugs did not stop the threat from mosquitoes.

The treated nets block female mosquitoes from securing blood, which is necessary for them to reproduce. The insecticide also cut the life of the insects in half.

The World Health Organization has set a goal of stopping lymphatic filariasis as a public health problem by the year 2020. The WHO estimates that 1.4 billion people in 73 countries are at risk of the disease. Children are often infected, but they do not show signs of the disease until later in life.  

This Science in the News was written by Milagros Ardin and Kim Varzi. I’m Faith Lapidus.


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点击收听单词发音收听单词发音  

1 doughty Jk5zg     
adj.勇猛的,坚强的
参考例句:
  • Most of successful men have the characteristics of contumacy and doughty.绝大多数成功人士都有共同的特质:脾气倔强,性格刚强。
  • The doughty old man battled his illness with fierce determination.坚强的老人用巨大毅力与疾病作斗争。
2 promising BkQzsk     
adj.有希望的,有前途的
参考例句:
  • The results of the experiments are very promising.实验的结果充满了希望。
  • We're trying to bring along one or two promising young swimmers.我们正设法培养出一两名有前途的年轻游泳选手。
3 tuberculosis bprym     
n.结核病,肺结核
参考例句:
  • People used to go to special health spring to recover from tuberculosis.人们常去温泉疗养胜地治疗肺结核。
  • Tuberculosis is a curable disease.肺结核是一种可治愈的病。
4 specially Hviwq     
adv.特定地;特殊地;明确地
参考例句:
  • They are specially packaged so that they stack easily.它们经过特别包装以便于堆放。
  • The machine was designed specially for demolishing old buildings.这种机器是专为拆毁旧楼房而设计的。
5 investigators e970f9140785518a87fc81641b7c89f7     
n.调查者,审查者( investigator的名词复数 )
参考例句:
  • This memo could be the smoking gun that investigators have been looking for. 这份备忘录可能是调查人员一直在寻找的证据。
  • The team consisted of six investigators and two secretaries. 这个团队由六个调查人员和两个秘书组成。 来自《简明英汉词典》
6 activates 78ec2b8b23e0120508757d953f1013d1     
使活动,起动,触发( activate的第三人称单数 )
参考例句:
  • Activates the window and displays it in its current size and position. 激活窗口,保持当前的大小及位置不变。
  • Pulling out the alarm switch activates alarm and pushing it deactivates it. 闹钟的开和关是通过拔出和按入闹铃开关实现的。
7 indigenous YbBzt     
adj.土产的,土生土长的,本地的
参考例句:
  • Each country has its own indigenous cultural tradition.每个国家都有自己本土的文化传统。
  • Indians were the indigenous inhabitants of America.印第安人是美洲的土著居民。
8 epidemic 5iTzz     
n.流行病;盛行;adj.流行性的,流传极广的
参考例句:
  • That kind of epidemic disease has long been stamped out.那种传染病早已绝迹。
  • The authorities tried to localise the epidemic.当局试图把流行病限制在局部范围。
9 provocative e0Jzj     
adj.挑衅的,煽动的,刺激的,挑逗的
参考例句:
  • She wore a very provocative dress.她穿了一件非常性感的裙子。
  • His provocative words only fueled the argument further.他的挑衅性讲话只能使争论进一步激化。
10 neolithic 9Gmx7     
adj.新石器时代的
参考例句:
  • Cattle were first domesticated in Neolithic times.新石器时代有人开始驯养牛。
  • The monument was Stone Age or Neolithic.该纪念碑是属于石器时代或新石器时代的。
11 domesticate PsnxD     
vt.驯养;使归化,使专注于家务
参考例句:
  • Many thousand years ago people learned how to domesticate animals.数千年以前人们就学会了饲养动物。
  • If you domesticate this raccoon,it will have trouble living in the wild.如果你驯养这只浣熊,它生活在野外将会有困难。
12 domesticated Lu2zBm     
adj.喜欢家庭生活的;(指动物)被驯养了的v.驯化( domesticate的过去式和过去分词 )
参考例句:
  • He is thoroughly domesticated and cooks a delicious chicken casserole. 他精于家务,烹制的砂锅炖小鸡非常可口。 来自《简明英汉词典》
  • The donkey is a domesticated form of the African wild ass. 驴是非洲野驴的一种已驯化的品种。 来自《简明英汉词典》
13 domestication a412c94ddc4dddbce0e57281001e9ede     
n.驯养,驯化
参考例句:
  • The first was the domestication of animals. 第一个阶段是驯养动物。 来自《简明英汉词典》
  • In northwestern China, there is no evidence for endemic domestication of any animals. 在中国西北,没有任何当地动物驯化的迹象。 来自辞典例句
14 susceptible 4rrw7     
adj.过敏的,敏感的;易动感情的,易受感动的
参考例句:
  • Children are more susceptible than adults.孩子比成人易受感动。
  • We are all susceptible to advertising.我们都易受广告的影响。
15 vaccines c9bb57973a82c1e95c7cd0f4988a1ded     
疫苗,痘苗( vaccine的名词复数 )
参考例句:
  • His team are at the forefront of scientific research into vaccines. 他的小组处于疫苗科研的最前沿。
  • The vaccines were kept cool in refrigerators. 疫苗放在冰箱中冷藏。
16 swelling OUzzd     
n.肿胀
参考例句:
  • Use ice to reduce the swelling. 用冰敷消肿。
  • There is a marked swelling of the lymph nodes. 淋巴结处有明显的肿块。
17 formerly ni3x9     
adv.从前,以前
参考例句:
  • We now enjoy these comforts of which formerly we had only heard.我们现在享受到了过去只是听说过的那些舒适条件。
  • This boat was formerly used on the rivers of China.这船从前航行在中国内河里。
18 malaria B2xyb     
n.疟疾
参考例句:
  • He had frequent attacks of malaria.他常患疟疾。
  • Malaria is a kind of serious malady.疟疾是一种严重的疾病。

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